Muscular_System_Structure_and_Function.pptx

Muscular system

1. Unit 3 – Muscular System Structure and Function VHS Anatomy K. Yam 2019-2020

2. I. Function of the Muscular System Key root words to know: Myo – or Mys - refers to “ muscle” Examples of terms that use the prefix = Myo cardial and Peri mys ium Sarco - refers to “flesh” which also refers to muscle Examples of terms that use the prefix = Sarco lemma

3. I. Function of the Muscular System Five key functions of the muscular system: Movement Stability Posture Organ protection Respiration Helps generate heat (maintains body temperature) Involves digestion Involves circulation

4. I. Function of the Muscular System Characteristics of Muscles: Excitability = can receive and respond to stimuli Contractibility = can shorten forcibly Extensibility = can be stretched or extended Elasticity = can recoil and resume resting length after being stretched

5. II. Structures of the Muscular System Level of Organization (listed from smallest functional unit to largest ) Muscular Structures in that Level Function of those Structures Molecules and Organelle Sarcomere Smallest contractile unit found inside a muscle fiber (cell) Myofibril Complex organelle m ade of the myofilaments actin and myosin Cell Muscle Fiber The cellular unit used to build muscle tissue Surrounded by an endomysium Tissue Fascicle Bundle of muscle cells Skeletal Tissue Muscular tissue that allows for voluntary movement , Striated structure Multinucleated Cardiac Tissue Muscular tissue that performs involuntary movement (heart beats without you thinking about it!); Striated in structure Smooth TIssue Muscle tissue that is visceral (lines hollow organs), Nonstriated in structure (looks smooth) Allows for involuntary movement

6. II. Structures of the Muscular System Level of Organization (listed from smallest functional unit to largest) Muscular Structures in that Level Function of those Structures Organs Whole Muscle Multiple Tissues working together including- Muscle Fibers (Cells) and Nerves Blood vessels (arteries & veins) – blood will supply energy and O 2 Connective Tissue Sheaths (wraps each cell and reinforces each muscle) Fascicle = bundle of muscle cells Perimysium = connective tissue that surrounds a fascicle Epimysium = connective tissue that surrounds a whole muscle

7. II. Structures of the Muscular System Anatomy of a muscle

8. III. Structure of a Muscle Fiber ( Cells of the Muscular System) Muscle fibers are multinucleated (more than 1 nucleus) Up to 30 cm long Specialized Structures found in the muscle fiber: Lots of mitochondria = need ATP (ENERGY) to do work! Sarcolemma = Cell/ Plasma membrane Sarcoplasm = Cytoplasm

9. III. Structure of a Muscle Fiber Myofibril = rod/ ropelike organelle specialized for contractions Contains sarcomere = smallest contractile unit of muscle fiber Region between two Z-discs Made up of myofilaments called myosin (thick) and actin (thin) Myosin = thick filaments that form cross-bridges with thin filaments to make muscles contract Actin = thin filaments made of two proteins called tropomyosin and troponin Has alternating Light (I) Bands and Dark (A) bands Sarcoplasmic reticulum (SR) = specialized smooth ER that surrounds a myofibril and stores and releases calcium T-tubule = part of sarcolemma, conducts nerve impulses to every sarcomere and triggers release of calcium from SR

10. III. Structure of a Muscle Fiber ( Cells of the Muscular System) Sarcolemma Sarcolemma Mitochondria Myofibril Nucleus T-tubules Sarcoplasmic reticulum MUSCLE FIBER DIAGRAM

11. III. Structure of a Muscle Fiber ( Cells of the Muscular System) MYOFIBRIL DIAGRAM

12. IV. Muscle Movements and Your Body When we think of muscles helping our movement, this usually involves skeletal muscle which must be attached to a bone through tendons. The tension created by the contraction of the skeletal muscle fibers is transferred to tendons. Each skeletal muscle has an origin and a point of insertion Origin = the end of the muscle attached to a fixed (stabilized) bone Insertion = moveable end of the muscle that attaches to the bone being pulled

13. IV. Muscle Movements and Your Body Examples of Muscle Origin and Insertion Points Muscle Origin Insertion Action Sternocleidomastoid Sternum/ Clavicle Temporal Bone (mastoid process); Occipital Bone Rotates and Tilts head side to side Biceps brachii Coracoid process; tubercle above glenoid cavity Radial tuberosity Bicep curl, allows palm of hand to point towards body while flexing Rectus abdominus Pubis Sternum; Ribs 5 and 7 Sitting up Sartorius Anterior-Superior Iliac spine Medial aspect of proximal tibia Moves back of lower legs up and back towards buttocks, as when kneeling; assists in moving thigh diagonally upward and outward Gastrocnemius Medial and lateral condyles of femur Posterior calcaneus Lowers the sole of the foot to the ground (foot tapping/ jumping), moving the back of the lower legs up and back towards the buttocks

14. IV. Muscle Movements and Your Body Role Muscles Play in Movement Role of Muscle What role does this play in muscle movement? Muscle Involved Using a Bicep Curl as an Example Agonist (prime mover) Muscle responsible for the primary movement Biceps Antagonist Opposes the movement of the agonists; helps regulate the agonist by adding resistance Triceps Synergist Assists the agonists and can add extra force or reduce an undesirable movement Brachioradialis and brachialis Fixator Immobilizes the bone or muscle origin Rotator Cuff Muscles

15. V. Major Muscles – Anterior View Quadriceps Masseter (jaw muscle)

16. VI. Major Muscles – Posterior View Hamstrings

17. VII. Other Muscles to Know